Workers slid heavy stones on paths covered with liquid and frozen water

By Ashley Yeager, 15:36 PM November 4, 2013

The heavy stones of the Forbidden City were probably slid into Beijing on ice paths.

Chinese workers could have used wheeled carts to move the 100-ton stones. But the laborers probably preferred sliding the chunks across ice because wheeled carts could hit bumps in the road and cause damage to the expensive stone, researchers report November 4 in the Proceedings of the National Academy of Sciences.